Enhanced Streaming Services in a Content Distribution Network

W ith the emergence of broadband access networks and powerful personal computer systems, the demand for network-delivered full-motion streaming video is growing. While the traditional Web service model can be applied to IP-based streaming content, the user experience of quality does not compare favorably with cable, satellite, or broadcast television. On the other hand, current television broadcasting technologies limit user choices and allow little or no on-demand access to video content. IP content distribution networks (CDNs) are special-purpose networks that provide scalability by distributing many servers across the Internet “close” to consumers. Consumers obtain content from these edge servers directly rather than from the origin server. Current CDNs support traditional Web content fairly well, but support for streaming content is typically less sophisticated and often limited to Webcasting, the delivery of fairly low-quality live streams, and clip acceleration, the distribution of low-to-medium-quality video clips. For Internet-based streaming to approach the same level of entertainment value as broadcast media, CDNs must drastically improve the quality of streaming they can support. Additionally, streaming CDNs will have to support more sophisticated services to accommodate new business models and new types of service offerings. Prism (Portal Infrastructure for Streaming Media) is a CDN architecture for distributing, storing, and delivering highquality streaming media over IP networks. The Prism-based stored-TV (STV) service allows users to select content based on the program’s name as well as the time it was aired. Content stored inside the network is accessible throughout the whole Prism infrastructure. For example, a user in the U.S. can access European TV content — both live and on-demand. Prism also allows users to specify content to be stored in a “network-VCR” type service. In this article, we introduce the components of the Prism architecture — content management, content discovery, and